The etiology of anorexia nervosa (AN) is poorly understood. Results from functional brain imaging studies investigating the neural profile of AN using cognitive and emotional task paradigms are difficult to reconcile. Task-related imaging studies often require a high level of compliance and can only partially explore the distributed nature and complexity of brain function. In this study, resting state functional connectivity imaging was used to investigate well-characterized brain networks potentially relevant to understand the neural mechanisms underlying the symptomatology and etiology of AN. Resting state functional magnetic resonance imaging data was obtained from 35 unmedicated female acute AN patients and 35 closely matched healthy controls female participants (HC) and decomposed using spatial group independent component analyses (ICA). Using validated templates, we identified components covering the fronto-parietal “control” network, the default mode network (DMN), the salience network, the visual and the sensory-motor network. Group comparison revealed an increased functional connectivity between the angular gyrus and the other parts of the fronto-parietal network in patients with AN in comparison to HC. Connectivity of the angular gyrus was positively associated with self-reported persistence in HC. In the DMN, AN patients also showed an increased functional connectivity strength in the anterior insula in comparison to HC. Anterior insula connectivity was associated with self-reported problems with interoceptive awareness. This study, with one of the largest sample to date, shows that acute AN is associated with abnormal brain connectivity in two major resting state networks (RSN). The finding of an increased functional connectivity in the fronto-parietal network adds novel support for the notion of AN as a disorder of excessive cognitive control, whereas the elevated functional connectivity of the anterior insula with the DMN may reflect the high levels of self- and body-focused ruminations when AN patients are at rest.

In anorexia nervosa (AN), volitional inhibition of rewarding behaviors, such as eating, involves a conflict between the desire to suppress appetite and the inherent motive to consume. This conflict is thought to have costs that carry over into daily life, e.g., triggering negative affect and/or recurring ruminations, which may ultimately impact long term outcome. Hence, increasing research effort is being dedicated to understand the link between emotional and ruminative processes in the etiology and maintenance of AN. We investigated whether affective states influence disorder-related rumination in AN applying "ecological momentary assessment", a method which allows the experimenter to gain insight into psychological processes in the natural environment and assess data in real time. Participants (AN = 37, healthy controls = 33) were given a smartphone for 14 days. A ringtone signaled at six random time-points each day to fill in a questionnaire, which gauged disorder-typical thoughts about food and weight as well as affective state. Analyses, applying hierarchical linear models confirmed that AN patients spend more time thinking about food, body shape and weight than controls (p < 0.001). Additionally, the results support the hypothesis that momentary negative affect (but not baseline depression (p = 0.56) or anxiety symptoms (p = 0.60) are positively associated with a higher amount of disorder-related rumination in patients (p < 0.001). Our findings are in line with theories which claim that ruminative thinking induces a vulnerability to negative stimuli which, in turn, fosters heightened negative affect. Thus, therapeutic interventions could be improved by implementing modules that specifically target disorder-related rumination.